Well, in addition to martial arts, I'd still be doing some jogging/running every (other) day for a few miles, and if I take up boxing I'll likely be going by bike cycling for 16 miles. My legs are pretty thick by nature already, whereas my arms are very thin.
I thought they might mean Muay Thai as well, but in both instances they also referred to it as kickboxing and in neither of them did they mention use of elbows and knees, which is one of the key differences between Muay Thai and kickboxing, if I'm correct.
Silently I'm hoping that one of them is kickboxing and the other Muay Thai, just so that I get to try out more stuff. But I doubt that'll be the case. So far, the nearest Muay Thai club I've found is a good 20 miles away, which is way too far for my tastes.
EDIT: Found a Muay Thai club in one of the other towns around!